Investigation of the Role of Membrane-Induced Conformational Change in the Function of the MinE Bacterial Cell Division Regulator

Description

The Min system ensures that gram-negative bacteria undergo symmetric cell division. The three Min proteins, MinC, MinD, and MinE, display a dynamic pattern of subcellular organization on the inner cell membrane that directs division proteins to the mid-cell. This process is driven by the ATPase activity of MinD that is stimulated through its interaction s with Min E. A recent structure of MinE in complex with MinD suggests that MinE undergoes a dramatic conformational change to allow MinD - binding residues to be released from the MinE hydrophobic core. However, this structure used a MinE mutant designed to favor this conformational change, raising questions regarding the mechanism by which wild - type MinE can undergo this transition in vivo. One potential scenario that might explain this structural change involves a recently discovered interaction between MinE and the membrane surface. To investigate the possibility that lipid binding could induce this structural transition in MinE, circular dichroism and enzyme kinetics studies were carried out. These studies were also done on MinE mutants designed to either eliminate membrane binding or induce the conformational change involved in MinD - binding. The results demonstrated that a membrane induced conformational change does occur, and requires the presence of a key lipid - binding region at the N - terminus. However, removal of this sequence failed to alter the kinetics of MinE - stimulated MinD - catalyzed ATP hydrolysis. Overall, our results provide a step forward in our understanding of the role of the interaction between MinE and the membrane in the Min system, but also highlight the need for additional investigation before this system might be used as a novel antibiotic target for pathogenic, gram - negative bacteria such as Neisseria gonorrhoeae.